Question

Which of the following can act as oxidising as well as reducing agent? (a) \(\mathrm{H}_{2} \mathrm{O}_{2}\) (b) \(\mathrm{SO}_{3}\) (c) \(\mathrm{H}_{2} \mathrm{SO}_{4}\) (d) \(\mathrm{HNO}_{3}\)

Short answer

\(\mathrm{H}_{2} \mathrm{O}_{2}\) can act as both oxidizing and reducing agent.

Step-by-step solution

Understand the concept of oxidizing and reducing agents

An oxidizing agent is a substance that gains electrons in a chemical reaction and is reduced. A reducing agent is a substance that loses electrons in a chemical reaction and is oxidized. A substance that can act as both an oxidizing and reducing agent must be able to both gain and lose electrons in different chemical reactions.

Investigate each substance's ability to gain and lose electrons

Examine each option to determine whether any of them can act as both an oxidizing agent and a reducing agent. (a) \(\mathrm{H}_{2} \mathrm{O}_{2}\) (hydrogen peroxide) can be reduced to water \(\mathrm{H}_{2} \mathrm{O}\) by gaining electrons or oxidized to \(\mathrm{O}_{2}\) by losing electrons. Thus, it fits the criteria. (b) \(\mathrm{SO}_{3}\) (sulfur trioxide) typically acts as an oxidizing agent by accepting electrons, and it is not commonly known to lose electrons to act as a reducing agent. (c) \(\mathrm{H}_{2} \mathrm{SO}_{4}\) (sulfuric acid) usually acts as an oxidizing agent and does not frequently act as a reducing agent. (d) \(\mathrm{HNO}_{3}\) (nitric acid) is a strong oxidizing agent and is not commonly known to act as a reducing agent.

Determine the correct answer

Based on the ability to both gain and lose electrons in different chemical reactions, the substance that can act as both an oxidizing and a reducing agent is \(\mathrm{H}_{2} \mathrm{O}_{2}\), hydrogen peroxide.

Key concepts

Chemical Reactions

In the fascinating world of chemistry, chemical reactions are the processes that transform substances into different substances. These reactions involve the breaking of bonds in reactants and the formation of new bonds in products. A chemical equation represents the reactants and products symbolically, much like a recipe details the required ingredients and the dish they make.

To understand chemical reactions, envision a dance where partners—atoms or molecules—exchange or share their hand-held glow sticks, symbolizing electrons. This swapping or sharing leads to the creation of new dances or substances. The interesting part is that these reactions are happening all around us, from the rusting of iron to the baking of a cake.

Ultimately, the goal is to balance the chemical equation, which means having the same number of each type of atom on both the reactant and product sides. Balancing equations ensures the conservation of mass and charge, adhering to the basic laws of physics and chemistry.

Electron Transfer

Imagine a bustling market where traders are busy exchanging goods; however, in the realm of atoms, the currency is electrons. Electron transfer is a fundamental aspect of chemical reactions that involves the movement of electrons from one atom, molecule, or ion to another.

Electron Donors and Acceptors

Atoms or molecules that give up electrons in this process are known as electron donors, while those that receive electrons are called electron acceptors. This electron exchange can drastically change the properties of these atoms or molecules, influencing their reactivity, color, and even their state of matter.

Oxidation Number

To keep track of electron movement, chemists use the concept of oxidation numbers, a hypothetical charge an atom would have if all bonds were completely ionic. Changes in oxidation numbers in a reaction indicate that electron transfer has occurred, providing clues to the substance's behavior as either an oxidizing or reducing agent.

Oxidation-Reduction (Redox) Reactions

Diving deeper into the heart of electron transfer, we encounter oxidation-reduction or redox reactions. These are reactions where oxidation and reduction occur simultaneously. Remember, oxidation is the loss of electrons, and reduction is the gain of electrons. In a redox reaction, one substance transfers electrons (undergoes oxidation) to another substance (which undergoes reduction).

Oxidizing and Reducing Agents

In our exercise, we looked for substances capable of playing dual roles—as both oxidizing and reducing agents. An oxidizing agent, also known as an oxidant, gains electrons and is thereby reduced. Conversely, a reducing agent loses electrons and is oxidized.

Substances like hydrogen peroxide (H_2O_2) are remarkable as they can do both—serve as an electron acceptor (oxidizing agent) or an electron donor (reducing agent), depending on the reaction conditions. This dual ability makes these substances versatile players in chemical reactions, capable of participating in a wide range of processes, including metabolic pathways in biology and industrial chemical syntheses.